Vibrating screen machines are used to separate aggregate particles such as topsoil, rock, crushed rock, gravel, sand, landfill material, recycling waste, compost, demolition debris, and the like (herein collectively referred to as “material”) into various sizes. These machines typically comprise one or more screens containing perforated plates, molded plastic with holes, wire cloth screens, or a plurality of evenly spaced fingers, which together act as a sieve through which the material is separated. In screens with a plurality of fingers, a charge of material typically is deposited on the receiving end of the screen and, as the machine vibrates, the fingers vibrate, conveying the material across the fingers to the discharge end. As the material is conveyed across the fingers, smaller material falls through the openings, allowing the larger material to continue across the fingers to a location separate from the smaller particles. Accordingly, the fingers must be strong enough to support the weight of the material, yet flexible enough to withstand vibration.
Most screens have rod-like metallic fingers that are individually bolted or welded to a support bracket, or clamped in a flexible clamp block to withstand vibrations. However, such screens have numerous parts and require extensive assembly time, making them expensive to manufacture and install. In addition, fingers that are rigidly attached by bolts and welds are subject to mechanical failure at their point of attachment, while clamped fingers may loosen during operation.
These fingers are also susceptible to abrasion and lodging of material between the fingers, which produces bowing and spacing between the fingers, resulting in poor screening. Attempts have been made to protect the metallic fingers by coating them with a thin layer of wear-resistant material. However, such coatings do not provide a sufficient volume of wear material to adequately protect the fingers during use. Alternatively, fingers made exclusively of flexible, wear-resistant material do not provide sufficient stiffness to satisfactorily separate materials. Therefore, it is desired to provide an inexpensive screen with fewer parts that eliminates the typical stress points and avoids loosening during operation. It is also desired to provide a screen having both increased wear-resistance and sufficient stiffness for separating materials according to particle size.
Additional information will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.